A bicycle rear suspension system improves bicycle comfort and performance, particularly for mountain bicycles, by allowing the rear wheel of the bicycle to track the terrain to some extent. This improves rider comfort by reducing the jarring effects felt when passing over uneven terrain on a so-called “hard tail” mountain bicycle (i.e., one that lacks a rear suspension system), and improves performance by increasing traction between the bicycle and the terrain while pedaling, turning and braking.
Various bicycle rear suspension systems have previously been developed. For example, U.S. Pat. No. 5,628,524 to Klassen et al. describes a rear suspension system in which a pair of rotatable links connects the rear triangle of a bicycle to the front triangle and a shock absorber, in a manner resulting in an s-shaped travel path of the rear wheel as the shock absorber is compressed. U.S. Pat. No. 8,066,297 also describes a rear suspension system including a pair of rotatable links connecting the rear triangle to the front triangle and a shock absorber, in which one of the links changes its direction of rotation as the shock absorber is compressed, resulting in improved riding characteristics.
One goal of a rear suspension system such as those described above is to provide a relatively “stiff” ride when ascending or passing over small bumps, but to provide a relatively “forgiving” ride when descending or passing over large bumps. This reduces the unwanted loss of pedaling energy due to unnecessary shock absorption, while preserving the desirable properties of the suspension system. There remains significant room for improvement in this regard.